This invention relates to the sweetening of beverages, including carbonated soft drinks and also tea and coffee. The soft drinks include especially those possessing a cola flavour and, in particular, calorie-reduce and dietary drinks.
Beverages such as cola, tea and coffee have been generally sweetened with sucrose or, for dietary reasons, with saccharin and its non-toxic, water-soluble salts. It is a peculiar nature of the cola flavour that it is particularly sensitive to the choice of sweetener and, therefore, it has been difficult to find a satisfactory replacement for sucrose. Thus, low-calorie formulations of colas based on saccharin usually include various taste modifiers to mask the unpleasant aftertaste of this sweetener, in the same way as when it is used in tea or coffee. It is also well known to modify the taste of saccharin by including in the composition another low-calorie sweetener, such as cyclamate (sodium, potassium, ammonium or calcium salts of cyclohexyl sulfamic acid), the combination providing a preferred quality of sweetness. Another well-known low-calorie sweetener proposed for such use with saccharin is aspartame (L-aspartyl-L-phenylalanine methyl ester; see GB 1,352,167).
Peptide sweeteners, such as aspartame, have been proposed as sweeteners for cola beverages, for example in GB 2,103,917A. Other peptide sweeteners proposed for such use include amino-protected aspartame (GB 2,092,161B); phenyl carbamyl L-aspartyl-L-phenylalanine derivatives (EP 107,597A); other aspartyl dipeptides (U.S. No. 3,879,372 and GB 1,359,123); amides of L-aspartyl-D-serine and L-aspartyl-D-cyclic amino acids (U.S. No. 4,399,163; U.S. No. 4,465,626 and U.S. No. 4,454,328); other L-aspartyl-L-phenylalanine esters (WO 83/01619A and EP 99960A) and tripeptides based on L-aspartic acid. L- and/or D-alanine and L- and/or D-valine (JP 036886 of 07.03.83). However, because of their general lack of stability in acidic environments, peptide sweeteners are not ideally suitaed for such use. Despite this, aspartame is being used widely in diet colas because it has a considerably better taste than saccharin.
Another low-calorie sweetener proposed for use in colas and other beverages is sucralose, 4,1'6'-trichloro-4,1,6'-trideoxy-galactosucrose. This and other chlorine-substituted sucrose sweeteners are disclosed in British Pat. No. 1,544,167 and in British Patent Application No. 2,104,063A.
It has been found that combination of these chlorosucrose sweeteners with certain other sweeteners having and accompanying bitter taste can lead to a marked synergy, that it to say an increase in the quantity of sweetness per unit weight of sweetening composition over its expected sweetness, calculated as the sum of the quantites of sweetness which would be provided by the individual sweeteners at the appropriate concentrations if used alone. Such sweetening compositions are disclosed in British Patent Application No. 2,098,848A. In these combinations, the sweeteners having a accompanying bitter taste include saccharin, acesulfame-K (the potassium salt of 3,4-dihydro-6-methyl-1,2,3-oxathiazin-4-one 2,2-dioxide) and stevioside. In complete contrast, the combination of sucralose with aspartame showed no synergy.
As previously mentioned, the cola flavour is particularly sensitive to the taste of sweeteners and the quality of sweetness is an important factor in determining which sweetener should be used in cola beverages. Since most artificial sweeteners can provide exactly the same quality of sweetness as sucrose, but are distinguishable from sucrose by the quality of sweetness, it is desirable to use as little of them as possible while maintaining the required sweetness level, usually equivalent in colas to around 8.5% sucrose and in tea and coffee to around 5% sucrose.